package leetcode.editor.cn;

//给你一个链表的头节点 head 和一个整数 val ，请你删除链表中所有满足 Node.val == val 的节点，并返回 新的头节点 。
//
// 
//
// 示例 1： 
// 
// 
//输入：head = [1,2,6,3,4,5,6], val = 6
//输出：[1,2,3,4,5]
// 
//
// 示例 2： 
//
// 
//输入：head = [], val = 1
//输出：[]
// 
//
// 示例 3： 
//
// 
//输入：head = [7,7,7,7], val = 7
//输出：[]
// 
//
// 
//
// 提示： 
//
// 
// 列表中的节点数目在范围 [0, 10⁴] 内 
// 1 <= Node.val <= 50 
// 0 <= val <= 50 
// 
//
// Related Topics 递归 链表 👍 1245 👎 0


//leetcode submit region begin(Prohibit modification and deletion)

import java.util.Objects;

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode() {}
 *     ListNode(int val) { this.val = val; }
 *     ListNode(int val, ListNode next) { this.val = val; this.next = next; }
 * }
 */
class Solution203 {
    public static void main(String[] args) {
        //1,2,6,3,4,5,6
        Solution203 solution = new Solution203();
        Solution203.ListNode head = new ListNode(1);
        ListNode node = head;
        node.next = new ListNode(2);
        node = node.next;
        node.next = new ListNode(6);
        node = node.next;
        node.next = new ListNode(3);
        node = node.next;
        node.next = new ListNode(4);
        node = node.next;
        node.next = new ListNode(5);
        node = node.next;
        node.next = new ListNode(6);
        node = node.next;
        head = solution.removeElements(head,1);
        System.out.println(head);
    }
    public ListNode removeElements(ListNode head, int val) {
        ListNode pre = new ListNode(Integer.MAX_VALUE,head);
        pre.next = head;
        ListNode preHead = pre;
        while (preHead.next != null){
            ListNode next = preHead.next;
            if(Objects.equals(next.val,val)){
                preHead.next = next.next;
            }else {
                preHead = preHead.next;
            }
        }
        return pre.next;
    }

    private void handle(ListNode node, int val){
        if(node == null){
            return;
        }
        if(node.next.val != val){
            node = node.next;
        }else {
            ListNode tempNode = node.next;
            while (tempNode.next != null && tempNode.next.val == val){
                tempNode = tempNode.next;
            }
            node = tempNode.next;
        }
        handle(node,val);
    }

    static class ListNode{
        int val;
        ListNode next;
        ListNode() {}
        ListNode(int val) { this.val = val; }
        ListNode(int val, ListNode next) { this.val = val; this.next = next; }
    }
}
//leetcode submit region end(Prohibit modification and deletion)
